1. FIELD OF THE INVENTION
This invention relates to a transducer which uses surface acoustic waves as a means of detecting pressure, acceleration, temperature, stress or strain in a digital manner, and particularly to a transducer which utilizes surface acoustic waves to detect the surface path deformation of a flexible diaphragm which is subjected to an external load or force.
2. DESCRIPTION OF THE PRIOR ART
Pressure transducers for converting pressure into electronic signals compatible with testing, indicating and control systems are well known in the art. Many such pressure transducers contain elements such as magnets, coils, switching circuits, mechanical vibratory elements and resonant crystals. to produce digital outputs from the prior art pressure transducers, techniques such as pulse torquing and analog-to-digital conversion are also well known.
As technologies such as turbine engines and their controls are increasing in complexity and are being exposed to increasingly severe environments, it is desirable to have available a simple, inexpensive and rugged pressure transducer compatible with state-of-the-art advances in the technology. The availability fo small, rugged, reliable and relatively inexpensive digital computers has firmly established the use of such computers in advanced turbine engine controls. Prior art pressure transducers have not kept step with the turbine engine and control technology, and suffer from disadvantages such as cost, size, power consumption, reliability and sensitivity to shock, vibration, electromechanical interference and temperature variations. Many prior art transducers have analog outputs which are not directly compatible with advanced digital systems, and require additional electronic conversion devices.
The present invention incorporates recent advances in microelectronic technology and utilizes surface acoustic waves as a means of detecting gas or liquid pressure in a manner compatible with digital systems. The use of surface acoustic waves results in a pressure transducer which is small, rugged, inexpensive to fabricate, sensitive, reliable as a result of its integrated electronics fabrication techniques and having a low power consumption. The transducer may also be used to sense acceleration, temperature, stress or strain.